Treatment of complex sulfid ores.



- electricity.

GUY DE BEOHI, or routes-ENGLAND,

ASSIGNOR or ONE-HALF To REGINALD wYN-N RUCKER, OF LONDON, ENGLAND.

TREATIIENT OF QOMPLEXSU'LFID OBES.

Specification of Letters Patent.

Patented March 3, 1908- Application filed April 9| 1907- Serial No. 367371.

T 0 all whom it may concern,

Be it known that GUY DE BECHI, a subject of the King of Italy, residing at 36 Upper Marylebone street, in the county of London, England, chemical engineer, consulting and analytical chemist, has invented certain new and useful Improvements Relating to the Treatment-of (omplex Sulfid Ores, of whioh the following is a specification. I

This invention relates to the treatment of complex sulfid ores, and particularly of complex zinc bearing ores, as for example the ores from the Australian Broken Hill deposits the object being to effect the separation of the lead zinc in the first stage of the process in such a manner that the lead remains in the insoluble form and the whole of the zinc is obtained in the form of zinc sulfate the said metals being thus rendered incondition for metallurgical treatment in the known manner. I

Heretofore considerable difficulty has been experienced in treating such ores for effecting the extractionofthe metals therefrom, ow ing to the intimate mixture of the constituents which consist chiefly of zinc blende and galena, and to the difliculty of a complete extraction of the zinc by a wet process which will cleanly separate this metal from the.

other constituents of the ore.

The present invention is designed to separate the lead from the zinc by a wet process, whereby each metal is obtained in a compound of such purity as to render the final metallurgical treatment a matter of common knowledge, this result being obtained by chemical means entirely, without the-aid of I am aware that other methods of a somewhat similar character have been proposed for solving this problem; but there are reasons in each case which prevent success. For example, I may mention the process of Siemens and Halske, which however is chiefly based on the use of electricity, and that of MacArthur and Forrest which aims atdissolving all the metallic constituents of. the ore, the metals being subsequently separated in solution. My process, however, aims at dissolving the zinc only so as to se arate it easily and in a practical manner cm the other constituents of the ore.

According to this invention, the ore isfirst very finely ground or ulverizedpreferably to an impalpable powder and in this condias to expedite the chemical action.

tion may be heated to ebullition with an acid solution of ferric sulfate, the free acid being onlynecessar for the subsequent regeneration of the erric. solution .as herein after described. The reaction is rendered com: fpllete by subjectingthe ore to an excessively he grindin and under certain conditions it A may be advisable to heat under pressure so Thus, if ferric sulfate be used for leaching, the zinc is rendered soluble as zinc sulfate, while the sulfur remains with the insoluble residue, as free sulfur; the following e uation representing what is believed to be t e chemical reaction: Y

The solution which is free from lead is then filtered, the insoluble residuecontaining all the lead compounds, sulfur and gangue matterbeing dried and heated in a closed vessel so as to recover the sulfur by distillation, after which the remainder of the residue may be treated for the extraction of thelead in the usual way.- .The filtrate or solution,

which contains the zinc as soluble zinc sulfate quite free from leadand as ferrous sulfate, if allowed to cool, would yield crystals of zinc-iron sulfate. To avoid the crystallizing of the iron salt with the Zinc salt, the solution is then treated in such a manner as to convert the ferroussulfate into ferric sulfate, and for this purpose nitric acid may be employed, the nitrous fumes evolved] being transformed, by any well known means into nitric acid which may thus be used repeatedly. The solution thus treated contalns only the ferric sulfate together with the zinc sulfate formed during the leaching, and, by suitably cooling only, the zinc s'alt alone may be separated out as zinc sulfate crystals; the ferric sulfate being dried and calcined in a muffle furnace the acid fumes given ofi or resulting fromsuch treatment, being caused to pass into and be absorbed either by the ferric sulfate solution from which the zinc sulfate crystals have;

separated out,'or by water so as to condense said fumes to sulfuric acid. The ferric sulfate solution which has absorbed the fumes evolved from the calcining of the zinc sulfate,

may then be-u'sed to leach a fresh quantity of ground ore. The resultant compound obthe iron ohiefly much more soluble than'the zinc sulfate remains in the mother liquor. The zinc sulfate crystals may be compounds suitable for further tained from the calcining of the zinc sulfate will be found to consist of nearly pure Zinc oxid which may be converted into pure spelter free from lead for use in the arts or be subjected to further treatmentif desired.

The foregoing process for extracting and separating the zinc from lead and zincbcaring ores requires in theory no other raw materials than ore, coal and lluxes for the lead smelting, and the process is a cyclical one. In practice however, nitrate of soda in small quantities must be used to make good the inevitable mechanical losses in regenerating the ferric sulfate solution. The result attained is a nearly complete and clean separation of zinc and lead. in the form of mctallurgical treatment without the use if extraneous reagents. As regards "the other metals which maybe present in the treated ore, namely, copper, silver, and gold, these remain chiefly with the lead residue and. are recovered by the lead smelting, the'copper being recovered as'matte, and thesilver and gold as ,alloyswith the load as is usual.

When the ore containsmetals such asiron or manganese these may be dissolved and trans formed into soluble sulfates by the ferric sulfate. Under such circumstances the amount of iron contained in the reagent continually increases untilsome of the solution has'to be thrown away, or must be purified from the excess ofiron. The bestmanner of purification consists in the precipitating of the iron as ferric hydrate or insoluble basic sulfate by the zinc oXid obtained from a previous openation; this precipitation of eX cess of iron can be done at regular intervals so as to eliminate the iron which is dissolved from the ore. An appropriate quantity of the liquid is therefore boiled with a milk of zinc oxid obtained from a previous operation,

the zinc oxid'thus displacing the iron andgoing into solution as sulfate; the excess of iron, .as ferric hydrate or basic insoluble ferric sulfate, separated by filtration in the well known manner and the liquid is returned to the process), The ferric compound thus removed can be sold'as iron ore, converted into ocher or other marketable iron compounds, or can go to the lead smelting department to supply the iron for the slag.

As regards the manganese, it is first transformed into sulfate which goesv into solution till the latter becomes saturated with manganese; when this point is reached,- no more sulfate of manganese is, dissolved by boiling, because the sulfate of manganese is more soluble at a moderate temperature than at boiling point; for the same reason such solutions do not give crystals of mixed manganese sulfate and zinc sulfate by cooling; Therefore, all the manganese sulfate formed, remains, after a certain number of operations, with'the lead and silica residue;

l I t l l l i l l l l to solid manganese sulfatezor manganese oxid can be produced by calcining the sulfate. By these methods of purification of the liquids, the zincsulfatc process crystallizes out in a cominerically pure condition, giving by subsequent cafe-ination pure Zinc torting.

\Vhat I claim mid desire to secure by LettcrsPat-ent of the United Statesis:---

1. A cyclical. process for treating complex Hsulfidores containing'lead, and zinc. con- 7 sisting in grinding orpulverizing the ore to the condition of an" impal able. powder, treating the same with a solution oflerric sulfate, filteringthe solution' of ferrous sulfate and zinc sulfate sofformed from the insoluble lead residue. converting the ferrous sulfate to ferric sulfate by oxidation and subjecting them to acid fumes'evolved from the calcinationof the zinc sulfate obtained from a previous operation, crystallizing out the zinc sulfate and separating the same from the ferric sulfate solution, calcining the zinc sulfate, subjecting the zinc, and lead coin ounds separately to the usual nmtallurgicaf treatment-and using the regenerated ferric solution for t quantity of ore. U

2. A cyclical processfortreating complex 'sulfid ores containing lead and zinc con.- sisting in grinding or pulveriz'ing the ore to the condition of impalpable powder, treating the same with a solution of ferric sulfate, filtering the'solution'offerrous sulfate and zinc sulfate so formed from the insoluble lead residue, com orting the ferrous sulfate to ferric sulfate by oxidation. aided by sul he treatment of a further obtained by the oxid and pure spelter by rel t t furic acid, crystallizing out the zinc sulfate and separating the same from the. ferric sulfate solution, calcincing the zinc sulfate.

subjecting the zinc and lead compounds separately to the usual metallurgical treat ment, and using the regenerated ferricsolution for the treatment of a further quantit of ore,.and also utilizing the acid fumes, evolved from the aforesaid calcining of the zinc sulfate in the conversion by oxidation of the subsequently formed ferrous sulfate to ferric sulfate.

ln testimonywhereof I affix my 111 presence of two Witnesses.

our on Bncmj si gn at1 ire Witnesses:

J. SELLY WARDLE, WALTER J, SKERTEN.

Correction in Letters Patent No. 880,775.

It is hereby certified that in Letters PatentNo. 880,775, granted March 3, 1908, upon the application of Guy de Bechi, of London, the Treatment of Complex Sulfid Ores,

England, for an improvement in an error appears in the printed specification requiring correction,'ae followsz ln' line 15; page'l, after the word lead the word and should be inserted; and that the said Letters Patent should be read with this correction therein that the same may conform to therecord of the case in the Patent Ofiice.

Signed and sealed this 24th day of March, A. D., 1908.

[SEAL] C. C. BILLINGS, v P

Acting Commissioner of Patents, 

